function Event(){
  this.events = {}
}

Event.prototype.on = function(eventType, callBack){

}

Event.prototype.off = function(eventType, callBack){

}

Event.prototype.emit = function(eventType){

}

const callBack1 = function(){
  console.log(111)
}

const events = new Event()

events.on('click', events)

console.log(events)